Control strategy for plug-in hybrid electric vehicle

摘要

A method of controlling a plug-in hybrid electric vehicle (10 fig. 1) including an electric propulsion system (14), an engine (12), and a catalytic converter (38). The method comprises monitoring a state of charge (SoC) 68 of a battery (22) of the vehicle when in a charge depletion mode; determining a rate of depletion of the state of charge 70; estimating from the rate of depletion a duration of a depletion period that represents the time remaining until a minimum state of charge of the battery will be reached 72 and determining a duration of a warming period of the catalytic converter 78. The two figures of warming duration and depletion duration are then compared 80 with the engine being activated if the duration of the depletion period is less than or equal to the duration of the warming period 82. The exhaust gas from the engine can then warm the catalytic converter to its optimum or light-off temperature. The step of determining the warming duration may include monitoring the ambient temperature 76 and the pre-determined engine speed 74, where the engine speed may be an idle speed.